title: Causative factors of fracture nonunion: the proportions of mechanical, biological, patient-dependent, and patient-independent factors.
abstract: BACKGROUND
  Understanding the causative factors of fracture nonunion leads to both prevention and improvements in treatment. The purpose of this study was to understand the clinical characteristics and causative factors of nonunion in a case series.
  
  
  METHODS
  One hundred two consecutive patients with fracture nonunions of the extremities who were surgically treated in our hospital over the last decade were analyzed. Data were collected by reviewing medical charts. Radiographs were reviewed to classify the nonunion by radiographic appearance. Causative factors of nonunions were identified for each patient. Factors relating to inadequate mechanical stability or reduction and those relating to a decline in biological activity were investigated. Mechanical factors included inappropriate dynamization, inappropriate reduction, inappropriate surgical management, insufficient fixation, and conservative treatment. Surgical technical errors were identified through careful review by three experienced trauma surgeons. Biological activity factors included comminution and bone loss, open fracture, excessive surgical exposure, infection, previous radiation therapy, alcohol abuse, diabetes mellitus, smoking, genetic disorders, and metabolic disease or endocrine pathology. We also classified the causative factors as patient-dependent or patient-independent factors.
  
  
  RESULTS
  Of the 102 nonunions, 47 were oligotrophic, 22 were hypertrophic, 17 were atrophic, 12 were defect types, and 4 were comminuted. Twenty-four cases had factors of inadequate mechanical stability or reduction, 23 cases had biological factors, and 55 cases had both types of factors. Four cases had patient-dependent factors, 40 cases had patient-independent factors, and 58 cases had both types of factors.
  
  
  CONCLUSIONS
  Our results demonstrated that there were a considerable number of nonunions with causative factors which can be improved, such as inadequate fracture management.
authors.affiliation: Department of Orthopaedic Surgery, Kobe University Graduate School of Medicine, 7-5-1 Kusunoki-cho, Chuo-ku, Kobe, 650-0017, Japan, tniikura@med.kobe-u.ac.jp.
authors.forename: Takahiro
authors.initials: T
authors.lastname: Niikura
authors.forename: Sang Yang
authors.initials: SY
authors.lastname: Lee
authors.forename: Yoshitada
authors.initials: Y
authors.lastname: Sakai
authors.forename: Kotaro
authors.initials: K
authors.lastname: Nishida
authors.forename: Ryosuke
authors.initials: R
authors.lastname: Kuroda
authors.forename: Masahiro
authors.initials: M
authors.lastname: Kurosaka
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D005500:Follow-Up Studies; D005593:Fracture Fixation, Internal / Q000009:adverse effects*; D017102:Fracture Healing; D018460:Fractures, Comminuted / Q000000981:diagnostic imaging / Q000601:surgery*; D005599:Fractures, Ununited / Q000000981:diagnostic imaging / Q000453:epidemiology / Q000209:etiology*; D006230:Hand Injuries / Q000000981:diagnostic imaging / Q000601:surgery*; D006801:Humans; D015994:Incidence; D007564:Japan / Q000453:epidemiology; D007869:Leg Injuries / Q000000981:diagnostic imaging / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D011859:Radiography; D012307:Risk Factors; D013997:Time Factors; D055815:Young Adult